[SPARK-20543][SPARKR][FOLLOWUP] Don't skip tests on AppVeyor

## What changes were proposed in this pull request?

add environment

## How was this patch tested?

wait for appveyor run

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17878 from felixcheung/appveyorrcran.

(cherry picked from commit 7087e01)
Signed-off-by: Felix Cheung <felixcheung@apache.org>

R/pkg/inst/tests/testthat/test_sparkSQL.R

@@ -3126,7 +3126,7 @@ compare_list <- function(list1, list2) {
 
 # This should always be the **very last test** in this test file.
 test_that("No extra files are created in SPARK_HOME by starting session and making calls", {
-  skip_on_cran()
+  skip_on_cran() # skip because when run from R CMD check SPARK_HOME is not the current directory
 
   # Check that it is not creating any extra file.
   # Does not check the tempdir which would be cleaned up after.

appveyor.yml

@@ -48,6 +48,9 @@ install:
 build_script:
   - cmd: mvn -DskipTests -Psparkr -Phive -Phive-thriftserver package
 
+environment:
+  NOT_CRAN: true
+
 test_script:
   - cmd: .\bin\spark-submit2.cmd --conf spark.hadoop.fs.defaultFS="file:///" R\pkg\tests\run-all.R
 
@@ -56,4 +59,3 @@ notifications:
     on_build_success: false
     on_build_failure: false
     on_build_status_changed: false
-